Question: $ { \left[\begin{array}{rr}{2} & {-2} \\ {3} & {1} \\ {2} & {-1}\end{array}\right]+\left[\begin{array}{rr}{-1} & {-1} \\ {-2} & {1} \\ {2} & {4}\end{array}\right] = {?} } $
To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{2}+{-1} & {-2}+{-1} \\ {3}+{-2} & {1}+{1} \\ {2}+{2} & {-1}+{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{1} & {-3} \\ {1} & {2} \\ {4} & {3}\end{array}\right]}$